Members of Congress love to promote domestic companies by adding Buy American provisions to legislation. But as Rep. Bruce Braley discovered this week, it is not as easy as it would seem to require the government to buy U.S. products.

On Tuesday, the Iowa Democrat issued a news release announcing his intention to amend the spending bill currently on the House floor to require Congressional offices to buy American-made goods.

“Every day, I hear members in the House chamber talk about supporting American workers and the products they make,” Braley said in the statement. “This amendment makes us put our money where our mouth is.”

But the amendment would have achieved almost nothing.

It simply said that none of the money provided in the spending bill, which funds government operations for the rest of the fiscal year, could be used by “any office of the legislative branch” to purchase “any item that is not grown, reprocessed, reused or produced in the United States.” Because that is a very broad swath, the amendment adopted the terms and conditions of a World War II-era provision called the Berry Amendment, which requires the Defense Department to buy American goods.

But the Berry Amendment applies only to purchases of food, hand tools, fabrics, and fabric items such as tents and tarps. So Braley’s amendment would only apply to items that Congressional offices don’t buy in significant quantities.

The amendment was ultimately ruled out of order and the House will not vote on it, Braley’s spokeswoman said, but he remains committed to finding ways to expand government — and Congressional — purchases of U.S. goods.

Experts in procurement said Braley’s amendment touches a deeper reality: that it is very difficult to mandate the purchase of U.S. goods.

For example, a significant portion of the expenditures made by Congressional offices each year is for computers, copiers and other electronic devices, almost none of which are made in America.

Brandon Weber, managing partner of Union Built PC of Maryland, said his is one of the few American companies that actually assemble computers in the United States, and Congress doesn’t buy from him. Weber said his firm makes computers that meet the standards set out in the 2009 stimulus bill, which required the use of goods that were “wholly produced” in the United States or were “substantially transformed” here, in the case of goods containing foreign components.

That definition differs from other government requirements, which for decades have been based on the percentage of domestic content included in an item.

Even the more flexible language of the stimulus bill, formally known as the American Recovery and Reinvestment Act, has spawned hundreds of requests for waivers by entities building water treatment plants and other infrastructure projects that require specific parts that are not available from U.S. manufacturers.

Requesting a waiver launches a full bureaucratic process that “just has so much paperwork and public notice tied to it, it’s really difficult to navigate it,” said David Gallacher, an associate at the law firm of Sheppard Mullin Richter &amp; Hampton who helps clients sell to the federal government. “When you involve that exemption, a lot of it is simply an exercise in pushing paper around and putting it out for the world to see.”

Gallacher said the process can delay construction projects for months and add enormous cost and paperwork burdens for both the applicant and the government agency to prove that there is no American supplier so that foreign materials can be used.

“Buy America always makes good politics at least as far as the headline goes,” Gallacher said, but it is usually imposed “with complete ignorance to how this will actually be applied.”

For example, even after Buy America provisions are imposed, U.S. obligations under a host of trade treaties prohibit the government from favoring U.S. products over those from dozens of nations that are favored trading partners.

But these complications don’t keep Congress from buying American-made goods. In fact, it is already part of federal law that the Secretary of the Senate and the Chief Administrative Office of the House, the two offices that do the bulk of the purchasing for Congress, must “purchase only articles the growth and manufacture of the United States, provided the articles required can be procured of such growth and manufacture upon as good terms as to quality and price as are demanded for like articles of foreign growth and manufacture.”

So Braley’s amendment may not have been workable or germane, but it appears to be more or less the law of the land anyway.